Step-by-step mechanism



. April 9 .1. w. ALLEN 2,239,310

STEP-QBY-STEL" MECHANISM Filegi March '19, 1940 I I INVENTOR. Jose ob W. Al/e/r Patented Apr. 1941 f srar-nY-s'mr MECHANISM Joseph WQAllen, East Orange, N. J.,- assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application March 19,

1940, Serial No. 324,851

This invention relates to step-by-step mechanisnis, and particularly to those of the ratchet yp Q Objects of the invention are to provide improved means for causing step-by-step motion of a ratchet wheel, for maintaining operative relationship between the ratchet wheel and its .actuator, and for preventing undesired movement of the wheel in either direction.

These and other objects of the invention will become apparent from inspection of the follow ing specification when read with reference to the accompanying drawing wherein is illustrated the preferred embodiment of the invention. It is to be'expressly understood, however, that the .drawing is for the purpose of illustration only,

and is not designed as a definition of the limits of the invention, reference being had to the appended claims for this purpose.

In the drawing, Fig. 1 is a View in elevation (with certain parts broken away to improve clarity) of a device embodying the invention;

Fig. 2 is a similar'view, but showing a difierent stage in the cycle of operation; and

Fig. 3 is a view along the line H of Fig. 2.

the pivot bearing shaft 22 which journals the said pawl in side plates It and Illa of the armature assembly ll.

The armature, including the cross-plate 20, is of suitable magnetic material, while the resil-f lent strip (leaf spring) i8 is of non-magnetic material, so that energization of the winding of the electromagnet i2 attracts only the armature, to cause its movement from its position indicated in Fig. 1 to that indicated. in Fig. 2; the

leaf spring ll meanwhile lagging behind, due to -,its pre-set bias and its non-magnetic material,

and moving leftward (as viewed in Figs. land 2) only to the extent required by the pressure of the lever arm 2| thereupon, as the said lever arm (with pawl 'i) is carried leftward by reason of the pivotal connection with the armature as indicated at 22. During this leftward movement,

' the pressure of the spring it upon the lever arm 2! not only yieldably resists the movement of the armature and pawl l to the left, but also exerts a turning moment upon the said lever arm 2! about its fulcrum 22, wherefore the pawl 11 is In the drawing, reference character 5 desig- 1 nates a ratchet wheel secured-to a shaft 6 con-.

tituting a driving shaft for actuation of any associated mechanism .(not shown), the wheel having teeth successively engaged by a pair of pawls l and 8, the latter beingpivotally mounted in a supporting bracket 9, and the former being an arm of the armature assembly ii of an electro- Tmagnet i2. As shown, the armature assembly is" pivoted on a rock-shaft, l3 journaled in bearings it and I5 (Fig. 3) of the frame it which supports the electroet l2.

A flat strip ll of resilient metal, having one leg i9 thereofturne'd under and dented for fixation to a recess in the frame it (as indicated at H) and'the other leg thereof extending upwardly ad- ,iacent the cross-plate of the armature assembly tends to hold the pawl 'I in the position indi in Fig. 1', and to yieldably oppose movement thereof to the opposite extreme of its range of movement (Fig. 2), in response to passage of current through electromagnet l2. The strip 18 is curved to bear upon the portion of the rockshaft l3 intermediate the brackets II and- Iland is initially stressed so as. to exert a constantly continuously urged downward with respect to the teeth of the ratchet wheel E, thereby precluding the possibility of a miss in the next succeeding ratcheting action, such as might be produced if the pawl l were allowed to escape from actualcontact with the said teeth during its backward movement.

' Thus, the spring It hasthe two-fold function of, first, exerting pressure continuously during the backward movement of the pawl to hold said pawl iii-engagement with the teeth of the ratchet wheel, and secondly, constituting the force and agency by which the pawl is caused 'to moveforward again (to rotate the ratchet wheel another step) immediately following, and in response to,

cessation of current flow in the winding of'the electromagnet i2.

It should be noted that the second Pawl 8 functions to prevent reverse rotation of the ratchet wheel 5, while the block 24 (depending from the upward portion of the bracket 9). serves as a iimiting stop for the pawl I in its forward travel, thereby preventing over-travel, and a resultant possible over-rotation of the ratchet actInZJl iQSSure upon a rigid lever arm 2| having a fixed relationship to the pawl l, as by being positively fixed thereto, or- (as shown) integral" therewith, so as to swing with said pawl a bout mounted thereon, a ratchet actuator pivotally wheel; .A flat resilient strip extends along one side of pawl 8, as shown, and yields suffloiently to permit outward movement of pawl 8 as the ratchet wheel is rotated, step by step, by pawl 1.

What I claim is: 1. line combination, with a rock-shaiftDofan electromagnet having, an. armature pivotally mounted on said armature, at a point on said armature that is remote from said rock-shaft, and resilient means flexed about said rock-shaft to urge said ratchet actuator into ratchet engaging position, and to yieldably oppose movement of said armature upon passage of current through said electromagnet.

2. The combination, with a rock-shaft, of an electromagnet having an armature pivotally mounted thereon, a ratchet actuator pivotally mounted on said armature, at a point on said armature that is remote from said rock-shaft, an arm extending rigidly from said ratchet ac-' tuator, in a direction substantially perpendicular to the surface of said ratchet actuator, and resilient means flexed about said rock-shaft to engage said rigidly extending arm and thereby urge said ratchet actuator into ratchet engaging position, and to yieldably oppose movement of said armature upon passage of current through said electromagnet. 1

3. The combination, with a rock-shaft, of an electromagnet having an armature pivotally mounted thereon, a ratchet actuator pivotally mounted on said armature, at a point on said armature that is remote from said rock-shaft, resilient means flexed about said rock-shaft to urge said ratchet actuator into ratchet engaging position, and to yieldably oppose movement of said armature upon passage of current through said electromagnet, and means having a surface disposed in substantial parallelism with the surface of said ratchet actuator to limit the travel of said ratchet actuator in the ratchet actuating direction.

4. The combination, with a rock-shaft, of an electromagnet having an armature pivotally mounted thereon, a ratchet actuator pivotally mounted on said armature, at a point on said armature that is remote from said rock-shaft, an arm extending rigidly from said ratchet actuator, in a direction substantially perpendicular to the surface of said ratchet actuator, resilient means flexed about said rock-shaft to engage said rigidly extending arm and thereby urge said ratchet actuator into ratchet engaging position, and to yieldably oppose movement of said armature upon passage of current through said electromagnet, and means having a surface disposed in substantial parallelism with the surface of said ratchet actuator to limit the travel of said ratchet actuator in the ratchet actuating direction.

5. The combination, with a rock-shaft, of an electromagnet' having an armature pivotally mounted thereon, a work performing element pivotally mounted on said armature, at a point on mounted thereon, a work performing element pivotally mounted on said armature, at a point on said armature that is remote from said rockshaft, resilient means flexed about said rockshaft to urge said work performing element into work performing position, and to yieldably 0ppose movement of said armature upon passage of current through said electromagnet, and means having a surface disposed in substantial parallelism with the surface of said work performing element to limit the travel of said work performing element in the work performing direction.

'7. The combination, with a rock-shaft, of an electromagnet having an armature pivotally mounted thereon, a work performing element pivotaliy mounted on said armature, at a point on said armature that is remote from said rockshaft, an arm extending rigidly from said work performing element, in a direction substantially perpendicular to the surface of said work performing element, resilient means flexed about said rock-shaft to engage said rigidly extending arm and thereby urgesaid work performing element into work performing position, and to yieldably oppose movement of said armature upon passage of current through said electromagnet, and means having a surface disposed in substantial parallelism with the surface of said work performing element to limit the travel of said work performing element in the work performing direction.

8. The combination, with a rock-shaft, of an element pivotally mounted thereon, a ratchet actuator pivotally mounted on said element, at a point on said element that is remote from said rock-shaft, resilient means flexed about said rockshaft to urge said ratchet actuator into .ratchet engaging position, and to yieldably oppose movement of said element in a direction opposite to that in which said ratchet actuator is moved by said resilient means.

' JOSEPH W. ALLEN. 

